TG 1031, an attenuated recombinant vaccinia virus containing sequences coding for the human MUC-1, and Interleukin 2 (IL-2) genes, has been designed for use in human clinical applications, especially in oncology. The vector, vaccinia virus, has been used extensively to vaccinate against smallpox and the virus is known to be highly immunogenic. The second component of the product, MUC1, is a mucin producing gene which is pre-expressed in a variety of adenocarcinomas.